Trialkanoyloxysilanes

Abstract

Trialkanoyloxysilanes of the formula I R1-A1-A2-O-CnH2n-Si(OOCR2) 3 I wherein R1 is H or an alkyl group of 1-10 c atoms, wherein one or two non-adjacent CH2 groups may also be replaced by oxygen atoms, or is F, Cl, Br or CN, R2 is an alkyl group of 1-5 atoms, A1 and A2 are each 1,4-phenylene or 1,4-cyclohexylene groups and n is 2, 3, 4, 5 or 6, can be used for generating a homeotropic orientation of liquid-crystalline phases on surfaces.

What is claimed is: 
     
       1. A trialkanoyloxysilane of the formula   R.sup.1 --A.sup.1 --A.sup.2 --O--C.sub.n H.sub.2n --Si(OOCR.sup.2).sub.3     wherein R 1  is H, alkyl of 1-10 C atoms, alkyl of 1-10 C atoms wherein one or two non-adjacent CH 2  groups are replaced by oxygen atoms, F, Cl, Br or CN, R 2  is alkyl of 1-5 C atoms; A 1  and A 2  are independently each 1,4-phenylene (Phe) or 1,4-cyclohexylene (Cy) and n is 2, 3, 4, or 6.   
     
     
       2. 1-Triacetoxysilyl-3-(p-trans-4-propylcyclohexylphenoxy)-propane, a compound of claim 1. 
     
     
       3. A compound of claim 1 of the formula   R.sup.1 --Phe--Phe--O--C.sub.n H.sub.2n --Si(OOCR.sup.2).sub.3.     
     
     
       4. A compound of claim 1 of the formula   R.sup.1 --Cy--Phe--O--C.sub.n H.sub.2n --Si(OOCR.sup.2).sub.3.     
     
     
       5. A compound of claim 1 of the formula   R.sup.1 --Phe--Cy--O--C.sub.n H.sub.2n --Si(OOCR.sup.2).sub.3.     
     
     
       6. A compound of claim 1 of the formula   R.sup.1 --Cy--Cy--O--C.sub.n H.sub.2n --Si(OOCR.sup.2).sub.3.     
     
     
       7. A compound of claim 1 wherein R 1  is alkyl or alkyl containing oxygen atoms. 
     
     
       8. A compound of claim 1 wherein n is 3. 
     
     
       9. A compound of claim 1 wherein C n  H 2n  is --(CH 2 ) n  --. 
     
     
       10. A compound of claim 1 wherein all alkyl portions are straight chained. 
     
     
       11. A compound of claim 1 wherein R 2  is methyl. 
     
     
       12. In a liquid-crystalline dielectric medium useful for visual electronic display elements, and having at least two liquid-crystalline components, the improvement wherein at least one component is a compound of claim 1. 
     
     
       13. A dielectric of claim 12 wherein the amount of said compound is 0.01-1 wt %. 
     
     
       14. In an electro-optical visual electronic display element, comprising a liquid crystalline dielectric, the improvement wherein the dielectric is one of claim 12. 
     
     
       15. A substrate useful in visual electronic display elements coated with a layer of a compound of claim 1. 
     
     
       16. A coated substrate of claim 15 which is a glass substrate. 
     
     
       17. In a method for generating a homeotropic orientation of a liquid crystalline phase in contact with a surface comprising employing at said surface a substrate coated with a layer which facilitates said homeotropic orientation, the improvement wherein the coated substrate is one of claim 16. 
     
     
       18. In an electro-optical visual electronic display element, comprising a liquid crystalline dielectric, and in contact therewith, a substrate coated with a layer which facilitates a homeotropic orientation in said dielectric, the improvement wherein the coated substrate is one of claim 16. 
     
     
       19. A compound of the formula   R.sup.1 --A.sup.1 --A.sup.2 --O--C.sub.n H.sub.2n --SiCl.sub.3     wherein R 1 , is H, alkyl of 1-10 C atoms, alkyl of 1-10 C atoms wherein one or two nonadjacent CH 2  groups are replaced by oxygen atoms, F, Cl, Br or CN; A 1  and A 2  are independently each 1,4-phenylene (Phe) or 1,4-cyclohexylene (Cy); and n is 2, 3, 4, 5 or 6.